It is relatively common for a single processing node of a network to run multiple stacks that handle different protocols. For example, a node might contain a TCP/IP stack for communications via the Internet or a corporate intranet, and at the same time run another stack such as perhaps a SNA (System Communications Architecture) stack for communications with IBM mainframes or IBM AS/400 nodes running IBM's APPN (Advanced-Peer-to-Peer) architecture. It is less common for a single node to run multiple stacks of the same type, say two or more TCP/IP stacks as one example. However, for performance reasons, it becomes desirable to run multiple stacks when the traffic load exceeds that which can be processed efficiently through a single stack. Naturally, if multiple similar stacks are executing in a single node, then occasions arise in which packets must be passed between two of the similar stacks. For example, if application A, which is served by stack A, wishes to communicate with application B, which is served by stack B, then the A and B stacks must communicate with each other in the same manner as if stacks A and B were in different nodes. In fact, in the prior art, this is exactly how this inter-stack communication is accomplished. Actual physical links are assigned between the stacks in the same manner as physical links are assigned between stacks in different nodes.
FIG. 1 shows an example of this prior art arrangement. FIG. 1 shows a node 100 and two TCP/IP stacks A and B within the node 100. Communications are established between the two stacks A and B using physical links 112 and 114 and write and read devices, such as 104 through 110. The write and read devices 104 and 106 might be contained within the same communications adapter card. The same is true for devices 108 and 110. However, this is not necessarily true in all cases, and four separate devices may be required for this full-duplex connection. Also associated with the read and write devices are conventional control blocks (not shown) which are used to administer the devices. The physical links 112 and 114 are assigned in a conventional manner between the stacks, as if the stacks were in different nodes. Thus, it is apparent that, while this arrangement is satisfactory from a functional point of view, it requires real resources that can become expensive and difficult to administer.